• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.305-321
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• 2015

This study started with wondering whether the nonproportional model used in unit assessment for 2nd graders is appropriate or not for them. This study aims to explore the applicability of the nonproportional model to 2nd graders when they learn about numbers. To achieve this goal, we analyzed elementary mathematics textbooks, applied two kinds of tests to 2nd graders who have learned three-digit numbers by using the proportional model, and investigated their cognitive characteristics by interview. The results show that using the nonproportional model in the initial stages of 2nd grade can cause some didactical problems. Firstly, the nonproportional models were presented only in unit assessment without any learning activity with them in the 2nd grade textbook. Secondly, the size of each nonproportional model wasn't written on itself when it was presented. Thirdly, it was the most difficult type of nonproportional models that was introduced in the initial stages related to the nonproportional models. Fourthly, 2nd graders tend to have a great difficulty understanding the relationship of nonproportional models and to recognize the nonproportional model on the basis of the concept of place value. Finally, the question about the relationship between nonproportional models sticks to the context of multiplication, without considering the context of addition which is familiar to the students.

• Journal of Radiation Protection and Research
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• v.26 no.2
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• pp.101-111
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• 2001

To study the relationship between the DNA content of human chromosomes and their involvement in radiation-induced structural chromosome aberrations, the frequencies of translocations and dicentrics induced in human lymphocytes after in vitro exposure to 2Gy of x-tay were analysed by fluorescence in situ hybridization(FISH). Single whole chromosome probes(WCP), specific for chromosomes 1, 2, 4, 7, 8, 9, and 21 and triple combination of probes tot chromosome 1, 2 & 4 were used separately. A significant deviation of the frequency of symmetrical translocation and dicentrics from a DNA-proportional distribution was observed. Chromosomes 2, 7, 8, 9 and 21 were less frequently involved in the formation of symmetrical translocations and dicentrics than expected, whereas chromosomes 1 and 4 were more frequently involved. Chromosome 2 and 4 showed a higher frequency of acentric fragments. When triple combination probe for chromosome 1, 2 & 4 was used, no differences were found between the observed and expected frequency of exchange type aberrations. The results showed that the frequency of radiation-induced chromosome aberrations was not proportional to DNA contents, suggesting the difference in the susceptibility to specific aberrations among individual chromosomes. The results also indicated that the FISH technique with combination of probes for chromosome 1, 2 & 4 was useful for radiation biodosimetry.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.999-1003
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• 2014

Objective: To validate the relationship between MACC1 and 6-phosphofructo-2-kinase/fructose 2, 6 bisphosphatase (PFKFB2) expression as well as its clinicopathological features and prognostic significance in hepatocellular carcinoma. Methods: By using immunohistochemistry, we investigated the MACC1 and PFKFB2 protein expression in 60 pairs of hepatocellular carcinoma and corresponding non-tumor tissues. Using the Mann-Whitney U test, the Chi-square test, Kaplan-Meier survival analysis, Cox proportional hazard regression analysis and Spearman analysis, we studied the relationship between MACC1 and PFKFB2 protein expression and postoperative overall survival (OS) of the HCC patients. Results: MACC1 and PFKFB2 positive staining rates were significantly higher in hepatocellular carcinoma than in the corresponding nontumor tissues (P=0.012 and 0.04, respectively). The clinicopathological features evaluation revealed that positive expression of MACC1 was associated with a high Edmondson classification (P=0.007) and advanced TNM stage (P=0.027). Similar findings were evident for PFKFB2 expression (P=0.002 and P=0.027). MACC1 and PFKFB2 positive expression was associated with a lower OS rate (P=0.004 and 0.03, respectively). Kaplan-Meier survival and Cox proportional hazard regression analyses revealed MACC1 positive expression to be a prognostic factor for postoperative OS, but PFKFB was not. Conclusion: Highly expressed MACC1 and PFKFB2 protein were associated with TNM stage, Edmondson-Steier classification and overall survival. MACC1 may affect tumor metabolism partly through expression and phophorylation of PFKFB2.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.472-477
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• 2016

We studied the effects of anodic oxidation treatments of carbon fibers on interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites with various current densities. The surface of treated carbon fibers was characterized by atomic force microscope (AFM), field emission-scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The interlaminar shear strength (ILSS) of the composites was determined by a short beam shear test. This result showed that both the roughness and oxygen group of the carbon fibers surface increased in proportion to the current density. After anodic-oxidation-treated, the ILSS also increased as a function of the current density. In addition, the proportional relationship between ILSS and phenolic hydroxyl group was confirmed. The ILSS of the CF-2.0 sample increased by 4% compared to that of the CF-AS sample, because the anodic oxidation treatment increased the oxygen group and roughness on the carbon fibers surface, which leading to the improvement of the interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites. Among these, the phenolic hydroxyl group which has the proportional relationship with ILSS is found to be the most important factor for improving the interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.10-18
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• 2000

Nondestructive testing(NDT) by using ultrasonic sound is widely applied to wood for grading, moisture and defect detecting, estimating degree of decay, etc. Before practicing such application, basic relationships between ultrasonic transmission and wood properties shall be studied first. In this study, ultrasonic NDT was applied to larch and red pine to investigate the effects of moisture content and slope of grain on ultrasonic transmission speed. Specimens for testing about moisture content were prepared to have moisture content of green state, 30%, 20%, 10% and oven-dry state. Specimens for testing about slope of grain were prepared to have grain angle of 0, 15, 30, 45, 60, 75 and 90 degree in the tangential direction. Ultrasonic transmission speed was inversely proportional to moisture content in low range of moisture content under around 30% that was considered to be close to fiber saturation point. In high moisture content range above 30%, the ultrasonic transmission speed was almost constant. The same trend was observed in the relationships between compressive strength and moisture content. Slope of grain also had inversely proportional relationship with ultrasonic transmission speed and compressive strength. The relationship between compressive strength and ultrasonic transmission speed could be expressed by a linear equation.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.65-79
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• 2019

In this study, simple regression and multiple regression analyses were performed to analyze the relationship between breccia and clay content and shear strength in fault cores. The results of the simple regression analysis performed for each rock (andesitic rock, granite, and sedimentary rock) and three levels of normal stress (${\sigma}_n=54$, 108, 162 kPa), reveal that the shear strength is proportional to breccia content and inversely proportional to clay content. Furthermore, as normal stress increases, the shear strength is influenced by the change in component content, correlating more strongly with clay content than with breccia content. In the multiple regression analysis, which considers both breccia and clay content, the shear strength is found to be more sensitive to the change in breccia content than to that of clay. As a result, the most suitable regression model for each rock is proposed by comparing the coefficients of determination ($R^2$) estimated from the simple regression analysis with those from the multiple regression analysis. The proposed models show high coefficients of determination of $R^2=0.624-0.830$.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.483-488
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• 2015

Objective : The purposes of this study was to analyze the locomotive movement of forelimbs according to changes in velocities in the quadruped cadence of horses. Methods : Horses selected as subjects consisted of Jeju pony horses (heights of withers: $1.23{\pm}0.51$). Two camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) were used to capture the movement of the horses' forelimbs at a rate of 60 frames/sec. Additionally, raw data was collected from Kwon3D XP motion analysis package ver 4.0 program (Visol, Korea) with DARTFISH (DFKREA., Korea) video software solution. The variables analyzed consisted of 1 step lengths, 1 stride lengths, stance time, swing time, 1 stride time, velocity while walking, and trot of the horses. A two-way ANOVA and paired t-test of the variables by velocity and phase were treated at .05 level of significant difference, statistically. Results : The time elapsed of walk(stance: 0.63 sec[63.86%], swing: 0.35 sec[36.14%], 1 stride time: 0.99 sec respectively) showed significant difference with more delay than that of trot(stance: 0.29 sec[45.73%], swing: 0.34 sec[54.27% ], 1 stride time: 0.63 sec respectively), and also showed significant difference at trot in interaction (stance time>tort swing>walk swing>walk stance). The 1 step lengths and stride lengths in trot showed significant difference with longer than that of walk. Velocity of Trot showed significant difference statistically with higher than that of walk Conclusion : The horses' velocity during 1 step lengths and 1 stride lengths showed a proportional relationship, but the correlation between the horses' velocity and stance time showed a negative relationship during the quadruped cadence.

• Journal of Chest Surgery
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• v.46 no.6
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• pp.449-456
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• 2013

Background: Tumor recurrence is the most common cause of treatment failure, even after complete resection of early-stage non-small cell lung cancer (NSCLC). In this study, we investigated the prognosis of patients with early recurrence in order to identify independent risk factors related to early recurrence. Methods: Between February 1995 and December 2012, 242 patients who underwent surgical resection for stage I NSCLC at Dong-A University Hospital were reviewed. The factors predicting overall survival (OS) and early recurrence were investigated. We also investigated the relationship between the patterns and period of recurrence and clinicopathological factors. Results: For patients with stage IA and IB NSCLC, the 5-year OS rate was 75.7% and 57.3% (p=0.006), respectively. A multivariate Cox proportional hazards model demonstrated that gender (p=0.004), comorbidity number (p=0.038), resection type (p=0.002), and tumor size (p=0.022) were the statistically significant predictors of OS. Moreover, the multivariate analysis revealed that smoking history (p=0.023) and histologic grade (p=0.012) were the independent predictors of early recurrence. Additionally, only histologic grade (poor differentiation) was found to be significantly associated with a higher frequency of distant metastasis; there was no relationship between the patterns and period of recurrence and clinicopathological factors. Conclusion: The present study demonstrated that smoking history and histologic grade were independent prognostic factors for early recurrence within two years in patients with early-stage NSCLC. Patients with these predictive factors may be good candidates for adjuvant therapy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1199-1206
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• 2015

In this study, the exhaust gas of a diesel engine operating on biodiesel(BD) fuel(a mixture of diesel and soybean oil) was investigated for different fuel mixing ratios in the range of BD3 to BD100. The experiments were conducted using injection pressures of 400, 600, 800, 1000, and 1200 bar. The Pearson correlation coefficient and Spearman rank-order correlation coefficient were used to quantify the NOx and Soot emissions based on the fuel mixing ratio and injection pressure. Consequently, the Pearson correlation coefficient obtained for NOx and Soot emissions according to the mixing ratio and injection pressure was -0.811 and the corresponding Spearman rank-order correlation coefficient was -0.884, which indicated that the correlation of the NOx and Soot emissions was linear. Thus, the NOx and Soot have a trade-off relationship. Moreover, at each injection pressure, the Pearson correlation coefficient was a negative number, which indicated an inversely proportional relationship between NOx and Soot.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.283-288
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• 2007

In order to elucidate the relationship between the sludge retention time(SRT) and the toxicity of heavy metals, such as copper (Cu), cadmium(Cd), and zinc(Zn), in sequencing batch reactor(SBR) process, IC50 was estimated with measuring of INT-dehydrogenase activity in variable SRTs. When the concentrations of heavy metals were increased, the activity of INT-dehydrogenase was gradually decreased indicating the heavy metals inhibit bacterial activity. Cu showed higher toxicity than Zn and Cd. $IC_{50}$ of Cu, Cd, and Zn ranged from $0.37\sim1.96$ mg/L, $15.4\sim16.9$ mg/L, and $9.70\sim23.4$ mg/L, respectively. The toxicity of Cu and Zn was reversely proportional to the length of SRT. It is probably caused by the increased concentration of extracellular polymeric substances in longer SRT which absorb heavy metals. Therefore, the operation of SBR with increased SRT is desirable in treatment of industrial wastewater containing heavy metals.